1. Overview 3 2 Introduction Design Analysis Fabrication Testing
Conclusions 4 5

2. AFRL Multi-Satellite Deployment NASA Shuttle Hitchhiker
Introduction
Virginia Tech Ionospheric Scintillation Measurement Mission (VTISMM) aka HokieSat
Ionospheric Observation Nanosatellite Formation (ION-F)
Utah State University
University of Washington
Virginia Tech
University Nanosatellite Program
2 stacks of 3 satellites
Sponsors: AFRL, AFOSR, DARPA, NASA GSFC, SDL
University Nanosatellites
AFRL Multi-Satellite Deployment
System (MSDS)
NASA Shuttle Hitchhiker
Experiment Launch
System (SHELS)

3. Design Internal Configuration Crosslink Components Cameras Power
Processing Unit
Torque Coils (3)
Magnetometer
Camera
Pulsed Plasma
Thrusters (2)
Camera
Battery Enclosure
Downlink Transmitter
Electronics Enclosure
Rate Gyros (3)

4. Fabrication
Composite structure comprised of 0.23” isogrid and 0.02” skin

5. Static Testing
Strength & stiffness test of structure without skin panels
Strength & stiffness test of loading fixture

6. Static Testing Strength & stiffness test of structure with skin panels
Experiment demonstrated a 32% gain in
stiffness in the cantilever mode due to addition of skins
Skins added less than 8% to the total mass

7. Modal (tap) Testing of Side Panels
Dynamic Testing
Modal (tap) Testing of Side Panels
Hammer provides impulsive input
Accelerometer measures accelerations used to characterize natural frequencies
Tap testing with and without skins
Verification of predictions of finite element analysis

8. Dynamic Testing Modal Testing of Side Panels (Without Skin) Mode 1
fn = 131 Hz
(vs 131 Hz predicted)
Mode 2
fn = 169 Hz
(vs 171 Hz predicted)

9. Dynamic Testing Modal Testing of Side Panels (With Skin) Mode 1
fn = 213 Hz
(vs 131 Hz without skin)
Mode 2
fn = 453 Hz
(vs 169 Hz without skin)

10. Dynamic Testing Modal Testing of Structure (Without Skins) Mode 1
fn = 245 Hz
(vs 249 Hz predicted)
Mode 2
fn = 272 Hz
(vs 263 Hz predicted)

11. Dynamic Testing Accelerometer Placement X-axis control Y-axis controlZ
Accelerometer Placement
X-axis control
Y-axis control
Z-axis control
Side panel 1
Side panel 2
Zenith panel
GPS (3 axis)
CPU (3 axis)
PPU (3 axis)
Battery box (3 axis)
Structure survived
all tests
Determined component locations to raise natural frequencies

12. Conclusions
Aluminum isogrid increases structural performance at reduced mass
Modal testing verifies accuracy of isogrid side panel finite element model within ~1% error
Modal testing demonstrates 26% increase in structural stiffness of side panel by adding thin aluminum skins
Analyses and experiments verify structure satisfies all Shuttle payload requirements

13. Acknowledgements Air Force Research Laboratory
Air Force Office of Scientific Research
Defense Advanced Research Projects
Agency
NASA Goddard Space Flight Center
NASA Wallops Flight Facility Test Center
University of Washington
Utah State University
Virginia Tech
Professor A. Wicks
Professor B. Love
Members of ION-F

15. Current Status Structures: done except for safety
Thermal: refining model. Thermal cycling component testing early fall.
Power: boards prototyped. Bboxes fabbed. Proto pack assembled, waiting on thermal chamber for testing.
Comm: testing ground station hardware. Final flight antenna fab underway.
ADCS: everything fabbed and functionally tested. Writing code.